In 'Nineteen Eighty-Four', George Orwell's prophetic novel about a future "world of lies", the author wrote about a device called the Memory Hole. It is used to alter any record, like a press report or a photograph, that no longer fits with the ever-changing policies of the Big Brother regime. Now imagine an historian trying to retrieve even a few of those records before they are doctored or destroyed. Would it be possible to reverse what Orwell described...